1. Field of the Invention
The present invention relates to hydrocyclone separators.
2. Background of the Invention
Hydrocyclones may be utilized for separating a liquid-solid mixture, a gas-liquid mixture, or a mixture of two liquids. Hydrocyclones have been found to be useful, for example, for the separation of an oil-water mixture.
When crude oil is extracted from the Earth's subsurface, the oil that is brought to the surface is typically contaminated with water and may also be contaminated with other substances. Before the oil is refined, the water must be substantially removed from the oil to allow the oil to be transported through a pipeline.
Because the separation of the water from the oil is never entirely complete, the water that is removed from the oil will still contain some amount of oil. Before this water can be reintroduced into the environment, the water must be treated to remove at least enough of the oil to meet environmental concerns. With increasingly stringent environmental regulations, the standards for water purity that must be met before the water can be returned to the environment are increasing.
One system utilized for treating the separated water to remove the residual oil employs a hydrocyclone, which uses centrifugal force to separate the oil from the water. The hydrocyclone is an apparatus that comprises a frustoconical shaped segment, into which the mixed flow to be separated is placed, via an inlet, into the wider end of the frustoconical shaped segment. As the fluid passes towards the narrower end of the frustoconical segment, a vortex is created, which causes the denser water phase of the mixture to be flung outwards while the lighter oil phase is displaced to the center of the frustoconical shaped segment.
A hydrocyclone will typically include a cylindrical tubular first segment that is contiguous with the opening at the wider end of a frustoconical shaped second segment, and a cylindrical tubular third segment that is contiguous with and extends from the narrower end of the frustoconical shaped segment. In order to produce the velocity and the centrifugal forces necessary for separation of the two substances, hydrocyclones have typically used a tangential entry opening into the first cylindrical tubular segment. The design of the hydrocyclone causes the entering fluid to begin spinning around the walls of the hydrocyclone, accelerating the fluid and converting the pressure of the incoming fluid into centrifugal force, up to several thousand times the force of gravity at the bottom of the frustoconical segment. The heavier material (the water) is forced outward in the cone and discharges through the underflow, typically located at the lower end of the cylindrical tubular third segment, while the lighter material (oil) moves toward the center and is discharged through the overflow, typically at the upper end of the cylindrical tubular first segment.